Also known as AST, this test is done as a part of liver function tests to assess the functioning of the liver. It is often ordered in conjunction with another liver enzyme, alanine aminotransferase (ALT)/SGPT to diagnose liver disorders. In most types of liver disease, the ALT level is higher than AST and the AST/ALT ratio will be low (less than 1). There are a few exceptions; the AST/ALT ratio is usually increased in alcoholic hepatitis, cirrhosis, and in the first day or two of acute hepatitis or injury from bile duct obstruction. With heart or muscle injury, AST is often much higher than ALT (often 3-5 times as high) and levels tend to stay higher than ALT for longer than with liver injury.